clapper
nounUK /ˈklæp.ər/
US /ˈklæp.ɚ/
A clapper is the small thing inside a bell that hits the sides to make it ring.
The bell rang loudly when the clapper struck its side.
OTHER MEANINGS
2. A person who claps their hands, especially in an audience.
The clappers in the front row cheered the loudest.
3. A wooden or plastic device that makes a loud clapping noise.
She used a clapper to scare the birds away from the garden.
4. The movable part of a film slate used to mark the start of a scene.
The director snapped the clapper and called action.